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Appendix V.

1003

rotation at different speeds when the car is turning a corner. >
The pinions lastly drive the hind road wheels by chains to the
chain wheels x x, the latter being fastened to the spokes by bolt
studs. The alternative to chain driving is the substitution of
a live axle at x, which is adopted in many cars, but the
universal joints required in the gear shaft render the method
objectionable, for allowance must always be made for deflection
of the car springs.

The steering hand wheel at p actuates by worm and spur
gearing and a lever, the steering rod r^ which in turn by lever
slews the wheels n and n^ round centres 2 and 3, for they are
both connected by levers s s and rod 4. Levers j s are not
parallel, so n and n2 turn through such different arcs that the
wheel centre lines will meet in a point coincident with the back
centre line x produced, all four wheels then truly rolling round
one centre in x; the principle being known as that of the
Ackermann gear. Other movements, such as change speed gear,
adjustment of carburettor, governor cut-out, &c., are all worked
from handles on steering pillar.

The cylinders are cooled by water kept circulating in jackets
by the pump N, and the hot water from cylinders is circulated
through the radiator / to be cooled, then back to water tank p to
be re-conducted to the engine jacket. The brake is provided at
Y Y, where two drums are gripped by blocks pulled tight as
required, by the lever z. Formerly, straps were used as at
p. 570, but the method being non-reversible, would not prevent the
car running backward down-hill, m is the engine-starting handle.

The Longuemare Carburettor, illustrated in Tigs. 920
and 921, is probably the very best example of a float-feed spray
carburettor. In Fig. 920 the petrol feeds a long pipe E, through
gauge at F, G being a cleaning cap. A is the float chamber and B
the float. The spindle H is weighted at its lower end, and sup-
ported by levers D if the float be at lowest position as shewn, so
that petrol enters freely. Gradually the float rises until the petrol
reaches level c, when the levers D rising with the float permit the
weighted needle to fall and close the lower orificej checking the
flow. When in action there is a delicate play of the float between

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